Fresh findings released in late September 2025 show the ionosphere displayed detectable pre-seismic disturbances 20–120 minutes before the November 28, 2021 M7.5 earthquake in northern Peru. By analyzing Total Electron Content (TEC) with GNSS/GPS receivers, researchers identified distinct pre-seismic ionospheric disturbances (PIDs) that strengthened as the mainshock approached. If validated…